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<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script>
        // var flag = !flag
        // console.log(flag);
        if(true)  {console.log('输入123') }else if (flse) alert('xxxx')
           
       
        function sum( a , b) { 
            return a + b 
         }
      
         sum( 2 )
     
        
    </script>
</body>
</html>